def draw_node(self, node: Node, painter):
"""Draw the specified node."""
painter.setBrush(
QBrush(
self.selected_color
if node is self.selected_node else self.regular_node_color,
Qt.SolidPattern,
))
node_position = node.get_position()
node_radius = Vector(node.get_radius()).repeat(2)
painter.drawEllipse(QPointF(*node_position), *node_radius)
if self.labels_checkbox.isChecked():
label = node.get_label()
# scale font down, depending on the length of the label of the node
painter.setFont(
QFont(self.font_family, self.font_size / len(label)))
# draw the node label within the node dimensions
painter.drawText(
QRectF(*(node_position - node_radius), *(2 * node_radius)),
Qt.AlignCenter,
label,
)
def get_vertex_position(self, n1: Node, n2: Node) -> Tuple[Vector, Vector]:
"""Return the position of the vertex on the screen."""
# positions of the nodes
n1_p = Vector(*n1.get_position())
n2_p = Vector(*n2.get_position())
# unit vector from n1 to n2
uv = (n2_p - n1_p).unit()
# start and end of the vertex to be drawn
start = n1_p + uv * n1.get_radius()
end = n2_p - uv * n2.get_radius()
if self.graph.is_directed():
# if the graph is directed and a vertex exists that goes the other way, we
# have to move the start end end so the vertexes don't overlap
if self.graph.does_vertex_exist(n2, n1):
start = start.rotated(self.arrow_separation, n1_p)
end = end.rotated(-self.arrow_separation, n2_p)
return start, end
def get_vertex_weight_rect(self, n1: Node, n2: Node, weight: float):
"""Get a RectF surrounding the weight of the node."""
r = self.weight_rectangle_size
# width adjusted to number of chars in weight label
adjusted_width = len(str(weight)) / 3 * r + r / 3
weight_vector = Vector(r if adjusted_width <= r else adjusted_width, r)
if n1 is n2:
# special case for a vertex pointing to itself
mid = n1.get_position() - Vector(r * 3, r * 4)
else:
start, end = self.get_vertex_position(n1, n2)
mid = (start + end) / 2
return QRectF(*(mid - weight_vector), *(2 * weight_vector))
def draw_vertex(self, n1: Node, n2: Node, weight: float, painter):
"""Draw the specified vertex."""
# special case for a node pointing to itself
if n1 is n2:
r = n1.get_radius()
x, y = n1.get_position()
painter.setPen(QPen(Qt.black, Qt.SolidLine))
painter.setBrush(QBrush(Qt.black, Qt.NoBrush))
painter.drawEllipse(QPointF(x - r / 2, y - r), r / 2, r / 2)
head = Vector(x, y) - Vector(0, r)
uv = Vector(0, 1)
painter.setBrush(QBrush(Qt.black, Qt.SolidPattern))
painter.drawPolygon(
QPointF(*head),
QPointF(*(head +
(-uv).rotated(radians(10)) * self.arrowhead_size)),
QPointF(*(head +
(-uv).rotated(radians(-50)) * self.arrowhead_size)),
)
else:
start, end = self.get_vertex_position(n1, n2)
# draw the head of a directed arrow, which is an equilateral triangle
if self.graph.is_directed():
uv = (end - start).unit()
painter.setBrush(QBrush(Qt.black, Qt.SolidPattern))
painter.drawPolygon(
QPointF(*end),
QPointF(
*(end +
(-uv).rotated(radians(30)) * self.arrowhead_size)),
QPointF(
*(end +
(-uv).rotated(radians(-30)) * self.arrowhead_size)),
)
painter.setPen(QPen(Qt.black, Qt.SolidLine))
painter.drawLine(QPointF(*start), QPointF(*end))
if self.graph.is_weighted():
# set color according to whether the vertex is selected or not
painter.setBrush(
QBrush(
self.selected_color if self.selected_vertex is not None and
((n1 is self.selected_vertex[0]
and n2 is self.selected_vertex[1]) or
(not self.graph.is_directed()
and n2 is self.selected_vertex[0]
and n1 is self.selected_vertex[1])) else
self.regular_vertex_weight_color,
Qt.SolidPattern,
))
weight_rectangle = self.get_vertex_weight_rect(n1, n2, weight)
painter.drawRect(weight_rectangle)
painter.setFont(QFont(self.font_family, int(self.font_size / 4)))
painter.setPen(QPen(Qt.white, Qt.SolidLine))
painter.drawText(weight_rectangle, Qt.AlignCenter, str(weight))
painter.setPen(QPen(Qt.black, Qt.SolidLine))
